1. Field of the Invention
The present invention is related to a backlight adjustment device and method thereof, and particularly to a backlight adjustment device of an RGBW display system and method thereof.
2. Description of the Prior Art
An RGBW display is a display which adds white light on a traditional RGB display. Because the white light does not need a color filter, the RGBW display can provide higher luminance than the traditional RGB display, and reduce power consumption of a backlight source. Compared to the RGB display, the RGBW display has two advantages: 1. the RGBW display can provide higher luminance at the same power consumption; and 2. the power consumption of the RGBW display is lower than that of the RGB display for the same luminance.
However, the RGBW display may decrease luminance of images when the RGBW display displays images with higher color saturation. Please refer to FIG. 1A and FIG. 1B. FIG. 1A is a diagram illustrating ratio of a sub-pixel area to a pixel area of the RGB display and ratio of a sub-pixel area to a pixel area of the RGBW display, and FIG. 1B is a diagram illustrating decrease in the luminance of the images as the RGBW display displays the images with the higher color saturation according to the prior art. As shown in FIG. 1B, taking pure red light as an example, gray levels of the red, green, and blue sub-pixels of the pure red light are (255, 0, 0). After adding a white sub-pixel (min(255, 0, 0)), gray levels of the red, green, blue, and white sub-pixels are (255, 0, 0, 0), so luminance of an RGBW pixel is decreased because area of the red sub-pixel is one fourth area of the RGBW pixel. Therefore, when the RGBW display of the prior art displays the images with lower color saturation, the RGBW display of the prior art has higher luminance at the same power consumption, however, when the RGBW display of the prior art displays the images with the higher color saturation, the images displayed by the RGBW display of the prior art have lower luminance.